KAJIAN PERUBAHAN PENGGUNAAN LAHAN TERHADAP LAJU EROSI PERMUKAAN DI DAERAH TANGKAPAN AIR WADUK MRICA

Abstract

Surface erosion is one of the determining variable of critical watershed, this related to river basin management
which always prioritized to critical land . Along with land use changes that lower watershed function, the
assessment of land use change on surface erosion becomes very important. The research was conducted on
catchment of Mrica reservoir, especially in Serayu, Merawu, Lumajang, and Liangan. The data input of land use
changes are from 2001-2009 that using Landsat TM and ALOS. The soil loss calculating method is MUSLE
(Modified Universal Soil Loss Equation). DEM data as a function of slope can be used to analyze at pixel level of
accuracy,soil data as erodibility function, and discharge as erosivity function. Musle analysis results indicate
that the average surface erosion of Mrica reservoir catchment are 16,775,896 tons per year or 11,183,931 m3 per
year, equivalent to the soil loss thickness as 16:13 mm per year. Result of land use changes effect to surface
erosion in the research area are moor, plantations, and scrub with R :0.85 positive correlation; 0.84, and 0.86.
Forest, correlates negatively to the surface erosion with R coefficient: 0.88. Thus, managing land use with high
correlation coefficient will greater impact to suppress soil loss/ erosion.